Bánh Tráng Nướng

Name: Bánh Tráng Nướng
Ingredients: 2 teaspoons fish sauce; 1/2 teaspoon sugar; 2 cloves garlic, finely grated; 8 ounces large shrimp, peeled, deveined and tails removed; 1/2 cup plus 2 teaspoons vegetable oil; 1 1/2 cups sliced scallions (5 to 6 total); Kosher salt; 1/4 cup Japanese mayonnaise; 2 tablespoons Asian chili garlic sauce; 2 large eggs; 1 Chinese sausage, sliced diagonally into 1/8-inch-thick pieces (about 1/3 cup); Eight 8- to 8.7-inch round rice paper wrappers; Cold water, as needed; Coarsely chopped cilantro leaves and soft stems, for topping; Crispy fried shallots, for topping